Research On Soil Moisture Monitor And Irrigation Control Of Orchard

With the adjustment of agricultural structure, the orchard area expands unceasingly, in recent years. The apple industry is the supporting mainstay of the development of rural economy in our country. It played an important role in improving the income of farmers, in processes agricultural structure adjustment and in earning foreign exchange through exports. But the water consumption for the irrigation of orchard is an increasing problem. The soil moisture is an important factor for accelerating the nutrients transformation and utilization of soil. Because of heavy irrigation, the soil has been so heavily leached. It’s going to raise a lot of problems with respect to environmental pollution. How to improve the utilization rate of water? It is the most important task for forestry sustainable development.In order to ensure the appropriate soil moisture for fruit growing and improve quantity and quality of fruit, the current research situation on soil moisture monitor and control technology of soil moisture both at home and abroad are discussed. The technology of foreign products is maturely, but it is expensive and unsuited to conditions in china. The technology of domestic products is low on automatic and intelligent degree, can’t satisfy the requirements of production management. Base on the microelectronics and computer control technique, a system of soil moisture monitor and irrigation control of orchard is designed.With the application of module design method, the system of soil moisture monitor and irrigation control of orchard is build up of host control module, data acquisition module, irrigation control module, liquid crystal display module(LCM), keyboard module, data memory module, wireless communication module, power supply module and upper computer software. The core of host control module is MSP430F149 microprocessor. MSP430 family of 16-bit single microcontrollers had ultra low power consumption is produced recently by TI Company. Low power design is playing a more and more important role in order to solve the problem of the shortage of electric energy. In the part of hardware design, the power supply of every module can be cut off when it is not operated. In the part of software design, microprocessor can run in active mode and five low power modes. The soil moisture probe can measure soil moisture by use of frequency domain reflectometry. It is characterized by low price and high performance and it is suitable for measuring soil moisture continuous, precisely and quickly. Sprinkler and drip irrigated systems are connected to irrigation control module. Precision irrigation is implemented by water pump motor control system. The Man-Machine Interface consisted of HG12864 LCM and keyboard has real time and history datum display and parameter settings function. FM31256 is serial nonvolatile memory characterized by no delay write, unlimited read/write endurance and low power consumption. Real-time clock integrated inside the chip provides time and date information accurately. Remote data communication is implemented between upper computer and lower position machine by wireless communication moduleThe software of system was written in C language. Every module can be called in the main program. Apple orchard irrigation is repeatable, iterative learning control theory can be used for repetitive control, so modify the next irrigation amount with iterative learning rate by using the last irrigation information. It can realize the accurate control of optimum soil moisture content. Because of the surface water takes a longer time to penetrate into the main active absorbing root systems area, the problem that real time control system can not obtain accurate feed back information of soil moisture content in time also can be solved by the iterative learning control algorithm.